The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
U.S. Pat. No. 7,410,621 describes a catalyst substrate with a peripheral mantle extending thereabout and having opposite end walls between which the substrate is disposed. At least one of the end walls acts as a forward seal which is maintained in close proximity with a corresponding sealing surface toward an inlet end of the catalytic converter housing. A retaining member is provided which maintains the sealing surfaces in close proximity to define a labyrinth seal therebetween.
U.S. Pat. No. 7,655,194 describes a catalyst substrate support for a corrugated foil honeycomb matrix defining a plurality of passages extending therethrough which are generally parallel to an axis. A peripheral mantle extends about an outer perimeter of the matrix and has inwardly extending flanges which extend across an outer periphery of the opposite end faces to cover outermost of the passages and restrict fluid flow between the peripheral mantle and the matrix. The outer perimeter of the matrix and the peripheral mantle may be spaced apart to define a gap for accommodating differential thermal expansions of the matrix and the peripheral mantle, the gap being smaller than a height of the inwardly extending flanges. Cross members secured to each of the opposite end faces of the matrix may transfer at least part of the gravitational load of the matrix to the mantle.
U.S. Pat. No. 7,919,052 describes securing a catalyst element in a catalytic converter with a bolted bar. The catalytic converter has a housing. The housing defines a conduit and has a support wall defining an opening in the conduit. A removable catalyst element covers the opening for treating an exhaust gas passing through the conduit. A removable bar abuts the catalyst element. A first end of the bar is anchored to the wall and a second end of the bar is bolted to the wall thus clamping the catalyst element between the wall and the bar.